N-(meta-toluyl)-methylpiperidines



United States Patent ffice 3,406,177 Patented Oct. 15, 1968 ABSTRACT OF THE DISCLOSURE N-(meta-toluyl)-methylpiperidines having the structural formula which are useful as insect repellents. The products are prepared by reacting a toluyl halide with a methylpiperidine in an anhydrous ethyl ether.

This invention relates to certain toluamides, to processes for their preparation, and to compositions of matter containing these compounds. More particularly, this invention relates to the new and useful compounds represented by the structural formula:

N- (meta-toluyl)-2-methylpiperidine, N-(meta-toluyl)-3-methylpiperidine, and N-(meta-toluyl)-4-methylpiperidine,

and to compositions of matter containing these compounds which are useful as pest repellents, i.e., they repel a large number of arthropods troublesome to men and animals because of stinging, biting, blood sucking or other annoying or dangerous activities including the carrying of disease germs. The foregoing structural formula shall be referred to hereinafter as Formula I. Certain of the toluamides of Formula I are particularly useful in spray compositions: as fly repellents. The utility of these compounds and the various compositions of matter containing these compounds is discused in detail infra.

Pest repellent compositions embodying the Formula 1 compounds can be provided in all forms customarily used to impart pest repellency. For example, one can produce sprays, solutions, emulsions, salves or ointments, laquers, paints or pastes, etc. The concentration of the active ingredients, which can be one or more of the aforesaid Formula 1 compounds, may be generally up to about 95% by weight of the composition which comprises a suitable vehicle or carrier, or if desired, a diluent.

Pesticides are generally not capable of either preventing pests from alighting or from biting, which may lead to infection; since the action of pesticides occurs generally after a certain latent period. Pest repellents serve the purpose of deterring pests and especially fiying insects from alighting and hence from biting and sucking. Hence pest repellents serve an important hygienic purpose and continuous attempts are made to improve the activity of these substances.

The first large scale application of repellents was made during the second world war by armies fighting and stationed in the tropics. Among the numerous substances which were tested during this period for their repellent which includes:

activity, only the following four have been used extensively on a commercial scale: phthalic 'acid dimethylester, succinic acid-di-n-butylester; 3,4-dihydro-2,2-dimethyl-4- 0X0-2-H-pyrane-6-carbonic acid-n-butylester, and the dimethyl ester of the cisbicyclo-(2,2,1)-5-heptene,2,3-dicarbonic acid. Today these compounds are obsolete and at the present time the most eificient repellents are 2-ethylhexane-1,3-diol and m-toluic acid di-ethyl-amide.

As appears from the enumeration of the heretofore known highly eificient repellents, they do not show any relationship between chemical composition and repellent activity.

-It was surprising to find, in the course of the investigation which resulted in the present invention that the Formula I compounds show repellent activity. This result could not be reasonably expected in view of the fact that compounds closely related to Formula I, i.e., N-(metatolnyl)-ethylpiperidine, do not show repellent activity.

Although it is of course possible to use the Formula I compound undiluted, it is usually more suitable, because it achieves even distribution easier and for economic reasons, to dilute the active substance with a solid, liquid or semi-solid carrier which can itself be a mixture of several substances. Such carriers can be of the most varied nature, but should preferably be harmless to warm-blooded animals, under the condition of use, i.e., in the quantities and concentration used in the chosen method of application.

As solid carriers there may be mentioned in particular, pulverulent organic or inorganic substances such as calcium phosphate, calcium carbonate, kaolin, calcined magnesia, kieselguhr, boric acid, cork meal, wood meal and, especially, talc and starch powder. These are impregnated with the active ingredient by known methods. Such dusting-agents are particularly suitable for dusting linen and clothing.

As liquid there comes into consideration both organic solvents and inorganic media which fulfill the requirements given above. Organic solvents, such as alcohols, esters, ethers and ketones, e.g., ethanol, propanol, benzyl alcohol, glycerol, propanone-Z, butanone-Z, cyclohexenol and other hydrated phenols, ethylacetate, glycol-monoethylether, cyclohexanone etc., are suitable as carriers both for use on the skin and for impregnating textiles and the like. The form found preferable for repelling insects from the human body is a solution of the compounds according to the invention in low-boiling solvents such as, e.g., isopropanol.

Solutions in oils of vegetable, animal, mineral and synthetic origin, such as, e.g., olive oil, arachis oil, castor oil and parafiin oil also come into consideration, such oils are useful for addition to solutions in low-boiling solvents.

For use in spraying, the known spray-solvents are particularly suitable, e.g., mineral oil distillates of the kerosene type, hydrogenated naphthalenes, and alkylated naphthlenes.

Emulsions and dispersions in an aqueous medium are suitable for purposes of spraying. Here the Formula I compound is mixed for this purpose, if necessary with the addition of organic solvents, with surface active agents which may be of the nonionic, cationic or anionic type. The concentrate can then be mixed with water to form either a water-in-oil or oil-in-water emulsion. When pressurized repellents are desired, compositions containing water-in-oil emulsions such as described in US. Patent 3,159,535 to Sesso et al. are preferred.

The following examples describe in detail compounds illustrative of the present invention and methods which have been devised for their preparation. However, the invention is not to be construed as limited thereby, either in spirit or in scope, since it will be apparent to those skilled in the art of organic synthesis that many modifications, both of materials and of methods, may be practiced without departing from the purpose and intent of this disclosure. Thoughout the examples hereinafter set forth, temperatures are given in degrees centigrade and 4 a i.e., N-(meta-toluyl)-3-methylpiperidine. That is, the latter compound was wholly inactive as an animal protectant spray composition against stable flies under the test conditions described below, whereas the former compounds relative amounts of materials in parts by weight, except 5 were extremely effective under similar conditions. All of as otherwise noted. the Formula I compounds were screened in animal pro- Pre aration tectant spray compositions according to the spot-test meth- P od described in detail by Roberts et al., in the Journal of The toluamides of Formulal can be synthesized by re- E i Entomology (1960), 53 (2), 301-303. g e g l fg s: z g i aPPrOPnate methyl 10 Animal protectant tests against stable flies g; 3235 Z ggfi met;1 t0luv1 chloride in In this test an area six inches in diameter on the side hydrous ethyl ether is added incrementally to an agitated of q i i 5 of 1 3 g i solution containing twice the molar amount of the approcon i l a 6 i c t r th r z priate purified methylpiperidine in anhydrous ethyl ether. 15 f e e 9 grea er a The reaction temperature is maintained at from about 10 A to /2 Incl} m length t IS chpPed so that the files can to about during the reaction and for about an hour reach the 5km to feed Flve or six test arezfs are ,spacgd after the addition is completed. The resultant white suspenon elthert q lf posmoned 5g 3 sion (the HCl salt of the corresponding methylpiperidine) amma Ion 15 1 e cows are con 6 is suction filtered and the cake washed with increments mdtvldual temperature and humldlty columns? Stalls an of anhydrous ethyl ether. The combined ethyl ether por- 2O SubJected sunlamp exposure four hours daily through tions are stored over potassium carbonate for about 12 the L fi d h d hours, filtered through Celite, and concentrated in vacuo. T 6 Stable files are con He Sal SIX me treatehtest The resultant oily amide is redistilled twice in vacuo i sigg :33; gi i fi gz ig ii i i i i gg; through an appropriate column. The yields and physical 2 I e a i g t a h ave 8 20 properties of the toluamides of the invention prepared acs i g zggg g z s i z z constant e g gg g to the foregomg method are set forth m Tab] temperature room for holding at 72 F. and 75% relative humidity.

TABLE I Repellency is measured by subtracting the percentage of Compound Percent r zonin PL, Rah-active flies that feed from 100%. When more than 20% of the Yleld 169x011 flies feed, the compound is considered to have failed as N-tmetgiifioluylm-methyl- 75. 9 110-112 0.04 1. 5393 a repellent. The compounds tested (at 5% by weight con- P at centration) are compared to a standard repellent compo- N- 1; -t1 l-8- th 1- 63.9 102.6104.6 0.01 1.5368

iifiriarfiel m y sition containing 0.05% by weight pyrethrms, which 18 g gg f g 115"HG/104 eifective for 4 days. The compounds tested are rated according to the following classifications: In addition to the foregoing, an elementary analysis of class I 1nefiective at 1 da these compounds established the presence of C, H, and N Class H Effective at 1 y in the percentages required for the particular compounds. Class IH Effective at days Thznrgreierrilcfeaggdagiliitiesginctionality was established by 40 Class IV Efiective at 4 or more days me o 1 A particularly preferied method of producing the tolw When tested according to the procedure described above, amides of the invention on a commercial scale comprises 2 5 223 353 25? i g ggfi agg fg 35; F introducing a meta-toluyl halide, such as meta-toluyl chloi adding g I and t a 3 ride, dissolved in an aromatic solvent such as benzene into ymeth 1 i g g g Class In H th l a benzene solution containing an equimolar amount of the y 1 l 2 h I 1 .posl on appropriate methylpiperidine. The reaction solution is Lammg g X efiectwe for refluxed until HCl gas ceases to be evolved. The resulting t i 1 2 -g- Con-mosaic; co-ntammg toluamide can be recovered according to conventional O g y p 1p en me m an e ecnve repellent for 2 procedures. In this reaction the HCl-methylpiperidine salt or is apparently formed but is believed to react with meta- Staple fly and mosqmto repellency toluyl chloride to form the amide. The resulting HCl gas Concentrattonscf one, two and five percent by weight is insoluble in the reaction solvent and accordingly is disdl et hyltohlaml.de and 0f y y charged from the reaction media as a volatile gas. pl p respectively were pp to X cheese c oth sleeves. The treated sleeves were air dried for about Animal protectant thirty minutes, wrapped around the forearm of human Two of the toluamides of Formula I, i.e., N-(metatest subiects and exposed for about three minutes to caged toluyl)-2-methylp1per1dine and N-(meta-toluyl)-4-methylpopulations of stable flies (Stom'oxys calcitrans) and mospiper dine, have unexpectedly been found to be uniquely quitoes (Aedes aegypti). The treated sleeves were reexeffective n animal protectant spray compositions particu- 6Q posed under the same conditions at one-half hour interlarly against stable tires. ThIS anlmal protectant property vals until they were non-repellent, i.e,. two bites during is particularly unobvious when these compounds are coman exposure qualifies the treated sleeve as non-repellent. pared with the third compound included in Formula I, Results of these tests are set forth in Table II below:

i TABLE 11 Compound bl erceini1t Period after first exposure (in hours) We y g 2 s 4.5 5.5 5.5 7 a 24 4s Do 3 R R NR NR Do 5 R R NB NB N-(meta-toluyl)-2-methy1p1peridine 1 R R R R R R R R N R Do 3 R R R R R R R R NR Do 5 R R R R R. R R R NR 1 One bite.

R=Repellent.

NR=Non-repellent, i.e., 2 or more bites per exposure.

To file cards (3" x 5") which were covered with a thin layer of molasses lens tissues were applied which had been treated with solutions of diethyltoluamide and N- (meta-toluyl)-2-methylpiperidine. The resultant test sandwiches were exposed at about thirty minute intervals to a cage containing from about 50 to about 75 starved adult houseflies (M. domestica). The treated test sandwich was considered non-repellent (N.R.) it about 6 such embodiments but may be varied within the scope of appended claims.

It is claimed: 1. A compound having the structural formula:

20 or more flies were found feeding through the repel- 1O lent treated test sandwich. The results of the test are set forth in Table III below. 2. The compound N-(meta-toluyl)-2-methylpiperidine.

TABLE III Percent Period after first exposure (in hours) Compound by weight Diethyltoluamide 1 NR NR Do 3 R NR 5 R R NR NR NR 1 R R N R NR 3 R R R R R R R R NR 5 R R R R R R R R R NR While the invention has been described in various em- 3. The compound N-(meta-toluyl)-3-methylpiperidine. bodiments, it is to be understood that it is not limited to 20 4. The compound N-(meta-toluyl)-4-methylpiperidine.

References Cited UNITED STATES PATENTS 2,166,120 6/1939 Bousquet 260294] 2,589,205 3/1952 Pohland 260294 3,051,620 8/1962 Abood 260294.7 3,222,203 12/1965 Skau et a1. 260294.7 2,476,913 7/ 1949 Reitsema 260294 2,498,430 2/1950 Lee 260294 2,890,150 6/1959 Baldwin 167-33 3,102,071 8/1963 Hodge 167-33 2,589,943 3/1952 Jensen 260294.3

OTHER REFERENCES Bunzel; Berichte, pp. 1053-57 (1889).

JAMES A. PATTEN, Primary Examiner.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, D.C. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,406,178 October 15, 1968 Henry Peter Crocker et 6.1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as show below:

Column 2, line 54, "nitroaniline should read"-- nitroanilines.. Column 6, line 70, "alkynyl of not more than carbon" shouldxread alkynyl of not more than six carbon Column 7, line 25, "2-furfurylbenzimidazole" should read 2-furylbenzimidazole Signed and sealed this 10th day of March 1970.

(SEAL) I i Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER,

Attesting Officer Commissioner of Patents 

